Emotion coaching (EC) is a parental emotion socialization style combining awareness and acceptance of children?s emotional experience with active validation of and teaching about children?s emotions. EC is related to lower externalizing and internalizing problems. Theory and research support the mediating role of emotion regulation (ER) in links of EC with children?s psychosocial adjustment. Thus, a developmental cascade model is proposed, with EC affecting children?s later ER, which then affects children?s internalizing and externalizing behavior problems (BP). One study to date has longitudinally investigated developmental shifts in EC, showing decreasing awareness and acceptance of children?s negative emotions and increasing endorsement of coaching negative emotions from 5 to 9 years of age.8 The proposed study will add to the literature by examining emotion coaching from 3 to 9 years of age, spanning the early childhood years when children make strides in understanding publically observable aspects of emotion as well as the middle childhood transition when children increase in understanding internal, mental aspects of emotions. Furthermore, the study will use behavioral observations of EC of both positive and negative emotions during object-focused mother-child interaction tasks, which provide naturally-occurring opportunities to capture mothers? discouragement of children?s emotions, an important element of the meta-emotion construct. Because there is evidence for differential effects of EC according to child temperament, the proposed study will also examine whether children?s temperament moderates links of EC with ER. In particular, children higher in negative affectivity (NA) may have greater need of parental EC because of their frequent and intense experience of negative emotions, and their need may also make them more receptive to parents? efforts. Thus, the developmental cascade model tested in the proposed study will be a moderated mediation model. Also, the model includes the potential bidirectional influence of children?s BP on parents? later EC. Specific aims are to examine (a) individual rank-order stability and mean-level change in maternal EC from early to middle childhood, and cross- task consistency in maternal EC in middle childhood, and (b) longitudinal associations of EC with BP through the mediator of ER, with NA included as a moderator of this developmental cascade and bidirectional relations of BP with later EC included. Aims will be accomplished through secondary analysis of data from a longitudinal study of psychobiology, temperament, and cognitive development that includes time points when children were 3, 4, 6 and 9 years of age. Videotaped mother-child interaction tasks will be re-purposed to observe EC. The study already includes standard age-appropriate measures of NA (maternal report and observed), ER (observed), and BP (maternal report) at each time point. The proposed research advances developmental science by rigorously examining stability, change, and cross-task consistency in EC, exploring temperament as a moderator, and testing a developmental cascade model long theorized in the literature.